Electric heater



E. N. LIGHTFOOT.

ELECTRIC HEATER. APPLICATION FILED JUNE 22,1920.

Patented Nov. 16, 1920.

4 SHEETS-SHEET I.

E. N. LIGHTFOOT.

ELECTRIC HEATER. APPLICATION FILED JUNE 22,1920.

1 ,359,400, Patented Nov. 16, 1920.

4 SHEETSSHEET 2.

1 5/67 2&7 Zdubrv ML E. N. LIGHTFOOT. ELECTRIC HEATER;

APPLICATION FILED JUNE 22,1'920.

1,359,400. Patented Nov. 16, 1920.

4 SHEETS-SHEET 3.

i/e/zfaf M077, /1/ L 005 E. N. LIGHTFOOT. ELECTRIC HEATER. nrucmou min JUNE 22. mo.

Patented Nov. 16, 1920.

4 SHEETS-SHEET 4- UNITED STATES PATENT OFFICE.

mm x. mm, or new toss, it. in, assrenon we ran cerium-1!v m. 00.; or mwaunx, wrscousm, a coarona'rros or wrsconsnr.

meme mum Toallwhom'itmay concern:

Be it known that I Enwm N. Lmn'rmoorr, a citizen of the finited States, residing at'New York, in the coun of Bronx and State of New York, have invented new and useful Improvements in- Electric. Heaters, ofwhich the following is e This invention relates -to an electric IQ heater.

, The heater to which invention rticularly apglim com rises in gene an elongated tu ular j st or a .terminel rigidly fastened to each en thereof la a resistor arranged within the jacket and connected between the terminals, and insulati'on between the resistor and the jacket.

' Among the objects of the invention is to provide a heater which is complete in itself,

so which is eficient and and which may be readily and economi y "Another. on, is a) rovide a 1......

which is bendable into di erent forms and as which, due'to its inherent structure, will retain the form into which it is bent.

In accordance with this inventionthe resistor is helical or winding and the insulation-is compacted and comp thereon. to Thejacket is ordinarily contracted crosswise tothoroughlycompren and compact v the insulation. 4 The com ressed insulation finnly- Me the residor in she and at in place endinsulates it from the and its turns or convolntions from as other.

The helicalor winding resistor mey its turns or convolutions extensively varied in diameter and number per inch to varyso throughout-a wide range its ohmic W Indication of Letters latent. Pgtented 0v. 16,

manufacs the resistorto the external muueun sue quite as, mm mm Io. seem.

Its insulation is so compacted that voids and interstices are practically eliminated.

Its insulation is. so compacted and com .QH upon the resistor and around and about volutions' are firmly kept in place and not disturbed when the heater is bent into the the fform in which-it is t will retain made or bent.

Its terminals are firmly held in position by thetgacket and do not produce any strain upon 4 c resistor. Its 'acket, insulation and resistor are not dlstur or strained by differential expansion' and contraction'thereof. I Its electrical and thermal characteristics are not changed when it isbent. 1 v Its resistor may have a high ohmic ree sistance. I

.Its externalheated surface may be small for a high ohmic resistance.

, for a given external heated surface varied ,thro a wide'range.

Its ength may be short for a resistor of h' h ohmic resistance.

t has low thermal resistance and high thermal conductivity between the redstor andwxternal heated surface.

I It has a low temperature dient' from surface where the heat is delivered. It may be operated at ahigh It may deliver heat at a high rate and at a low temperature. The views in are as follows: Figure 1 illustrates, partially in section,

a heater provided with a plug terminal;

Fig. 2 1s a sectional view onfline 2--2' of Its resistor may ha'veits ohmic resistance.

the same that the resistor and its contempera the accompanying drawings 1; i g.-3 is asectional view on line 3-3 of Fifi. 1; F ig. 4 is a sectional view on line H of Fi 5 illustrates, partially "in section, a heater provided with a cap terminal;

6 is a sectional view on line 66.of

Fi. J

his shows three resistors having widely Fig. 5;

ig. 7 is a sectional view online 77 of' difierent lengths and ohmic resistances and formed into helices having the same length and diameter and different numbers of turns to adapt them to the same-external heater surface;

Fig. 9 shows in swaging hammers;

F 1g. 10 is an end elevation of a pair of swaging hammers;

Fig. 11 is an elevation of a heater like that shown in Fig. 1;

f Fig. 12 shows the heater bent into helical Fig.13 shows the heater bent into reflexe form;

Fig. 14 shows a heater immersion heater;

Fig. 15 shows the heater bent into looped form;

Fig. 16 shows the looped heater mounted upon the surface of a plate;

Fig. 17 is a sectional of Fig. 16;

Fig. 18 shows the looped heater arranged in the groove formed in a plate;

Fig. 19 is asectional ew on line 19-19 bent to form an of Fig. 18;

Fig. 20 shows the looped heater embedded in aplate;

Fig. 21 is a sectional view on line 21-21 of Fig. 20; Fig. 22 diagrammatically illustrates a.

filling machine by which the insulation is introduced into the jacket;

Fig. 23 is an enlarged vertical section through the spacing tamper for holding the resistor in place within the jacket and com-.

pacting the insulation therein; and

Fig. 24 is a cross-sectional view on line 24-24 of Fig. 23.

i I Heater.

Figs. 1 to..4" show a heater which is provided with plug terminals.

The heater comprises an elon tedductile tubular jacket or casing 1; p ug terminals 2, one inserted in each end of the jacket and rigidly fastened thereto; a ductile helical resistor 3 arranged within the jacket and connected to the terminals; and insulation 4 compacted within the jacket and around and about the resistor.

Fi to 7 show a similar heater provide wlth'c'ap terminals instead of plug terminals.

The insulation is compacted when it is first put into the jacket, and then after the terminals are secured in position, the jacket is ordinarily contracted crosswise to further compress and ...compact the insulation. I

The dimensions whiaiobtain in a heater I for general purposesjare as follows:

Jacket: Length about thirty (30)inches.

vertical section a pair of view on line 17 -17 Outside diameter about one-quarter (1/4) inch (before contraction about five-sixteenth (5/16) inch.

Inside diameter about three-sixteenths (3/16) inch.

Helical resistor: Outside diameter of helix three-th1rtyseconds (3/32) inch.

Diameter of resistor wire,fr0m about one one hundred twent fifth (1/125) inch to about one-fortieth 1/40). inch.

Number of turns per inch from about eight (8) to about one hundred (100).

These dimensions may be varied according to'the purpose for which the heater is employed.

Jacket.

-the terminals permanently fastened in place,

the jacket is swaged or otherwise contracted crosswise to reduce its diameter and there by tightly compress the insulation upon and around and about the resistor.

The crosswise contraction of the jacket and the resultant compression of the insulation upon-the resistor tends to increase the cross section of the resistor and decrease its ohmic resistance and not to decrease its cross section and increase its ohmic resistance. 1

Further the jacket is not materially elongated or increased in length.

Figs. 9 and 10 show a pair of swaging hammers by means of which the jacket may be hammered or swaged to contract it. These hammers are placed in a machine by which they are rapidly vibrated and while the are vibrating the heater is moved back an forth and turned between the same until the jacket has been reduced in diameter throughout its le ductile material, for instance, nickel-chromium, nickel-steel, nickel-copper or other 7 resistance wire.

. The number of turns per inch in the helix I depends upon the lengths of wire and ohmic resistance to be obtained.

In order to facilitate making the resistor, the helix may first be wound with its turns close together and then stretched out to obtain the number of turns per inch necessary to give the required ohmic resistance.

Fig. 8 shows three helical resistors made from wire oithe maize and material.

, jacket.

These helices are different only in the number of turns per inch. Inasmuch as the number of turns per inch vary materially, the length of the wire and consequently the ohmic resistance is'widely varied.

Among the advantages which come from the helical resistor is that gives a relatively hi h ohmic resistance for a helix of a given ength and diameter and a given external heater surface, which ohmic resistance may be varied through a wide range by simply varying the number of turns per inch or the diameter of the turns or convolutions or both.

The resistor is provided at each end with a connector 5 by means of which it may be connected to the terminals.

This connectoris of greater cross section T eminals.

The plug terminal 2 (Fig. 1) has a plug which is inserted into the jacket and insulated therefrom by an insulating sleeve 7 The jacket is swaged or otherwise contracted upon the plug so as to firmly bind the terminal in place. v

The plug may be provided with an annular groove to allow an indentation to be made in the insulating sleeve andthe jacket to assist in fastening the terminal to the An insulating bushing 8 formed to cover the jacket may be threaded upon the lug. This bushing protects the insulating s eeve and further insulates the plug from the jacket.- I

The terminal is provided with a central has an indentation 9 swaged or otherwise formed therein to bind the connector thereto.

The cap terminal (Fig. 5) has a cap 10 which receives the jacket and is .insulated therefrom by an insulating sleeve 11. The cap is swaged or otherwise contracted upon the jacket to fasten it in position.

Insulation.

The insulation may 'be made" of various 7 materials and inserted in different ways.

the I dered insulation may be poured into the.

jacket and compacted is herein set forth.

After the heater is assembled and the terminalsfastened thereto, the jacket is finally ordinarily swaged or otherwise contracted crosswise to further com ress and compact l the insulation therein an around and about the resistor. The insulation insulates the resistor from the jacket and its turns from each other. It further holds the resistor and its'terminal in place so that the heater may be bent into various forms. a Forms of heater.

The heater is com lete in itself and-may be employed either a one or applied to heating appliances.

t is. originally straight in form as shown in Fig. 11 or may be bent into other forms as shown in Figs. 12 to 21 according to the purpose for which it is to be used.

F1 12 shows a helical heater, and Fig. 13 a re exed heater which may be used either alone or applied to heating appliance.

Fig. 14 showsan immersion heater which may be suspended within a vessel to heat 1i uid therein.

ig. 15 shows a looped heater which may be applied to a plate or. other body to be heate Figs. 16 and fastened to the surface of a plate.

Figs. 18 and 19 show the looped heater set in a grooved form in a plate.

Figs. 20 and 21 show the loo ed heater 17 show the looped heater I Y 10:s

'inclosed within a plate, the p ate being hole which receives the connector 5 and" either moldeduover the Same or formed two sections. N

Filling Figs. 22 to "24 illustrate a machine by which the in lation may be inserted and com acted. v

T e machine comprises in general a vibratory carrier 12 which is provided with an upper bracket 13 and a lower bracket 14 between which the heater is supported.

The up er bracket is .recessed to receive the end 0 the jacket and the lower bracket has a yielding seat 15 to receive the heater terminal, i v

The resistor is held in position'by a cord 16 attached thereto and connected to a, reel 17.

The insulation, powdered or granular, is carried in a can 18 mounted upon the carrier and having its spout located to feed the andconnected to the terminal, and mag nesium oxid compacted within the jacket insulation into the jacket through a hole in the bracket 13.

The carrier is mounted upon a spring 19 and is vibrated by means of a rotar cam 20.

A tubular tamper 21 provided with radial lugs 32, extends into the jacket and seryes to center and position the resistor and tamp the insulation.

This tamper is lifted and dropped by yieldingly rotary jaws 23.

When the machine is in operation, the carrier is vibrated up and down and the tamper lifted and ,dropped and accordingly the insulation is both shaken and tamped to compress the same within the jacket.

Of course various other machines may be provided and other ways adopted to apply the insulation.

lVhat is claimed is:

1. An electric heater complete in itself, comprising a winding resistor, insulation compacted and compressed around and about the same, a tubular metal jacket surrounding the insulation and contracted crosswise thereon to compact and compress the same, and a terminal rigidly fastened to the jacket and connected to the resistort 2. An electric heater complete in itself, comprising an elongated tubular metal jacket, a terminal ri idly fastened to and insulated from the acket, a winding re-' sistor arranged within the jacket and connected to the terminal, and insulation compacted within the jacket and compressed upon, around and about the resistor.

3. An electric heater complete in itself, comprising an elongated ductile, tubular metal jacket, a terminal rigidly fastened to and insulated from the jacket, a winding ductile resistor arranged within the jacket and compressed upon, around and about the resistor. 1

4. An. electric heater complete in itself, comprising an elongated tubular metal 'acket, a terminal ri idly fastened to and insulated from the jac et, a winding resistor arranged within the jacket and connected to the terminal, and granular magnesium oxid compacted within the jacket and around and about the resistor.

5. A bendable electric heater complete in itself and having in combination an elongated bendable tubular metal jacket, terminals rigidly fastened to the jacket, one at each end thereof, a winding resistor arranged within the jacket and connected to the terminals, and insulation compacted around and about the resistor by crosswise contraction of the jacket.

6. An electric heater complete in itself, comprising an elongated tubular metal jacket, a helical resistor arranged therein,

terminals rigidly fastened to the jacket and connecte closing the ends thereof, and insulation compacted within the jacket and around and about the resistor to insulate the resistor from the jacket and hold it in place.

7. An electric heater complete in itself comprising an elongated tubular metal jacket, a helical resistor arranged therein, terminals rigidly fastened to the jacket and closing the ends thereof, and magnesium oxid compacted within the jacket and around and about the resistor to insulate the resistor from the jacket and hold it in place.

8. An electric heater complete in itself comprising an elongated tubular metal jacket, 0. elical resistor arranged therein terminals rigidly fastened to the jacket an closing the ends thereof and granular magnesium oxid compacte within the jacket and around and about the resistor to insulate the resistor from the jacket and holdit in place.

9. An electricheater complete in itself, comprising a helical resistor, insulation around and about the resistor, a tubular metal jacket surrounding the insulation and contracted crosswise to compress and compact the insulation, and terminals connected to the resistor and rigidly fastened to the jacket and closing the ends thereof.

10. An electric heater complete in itself, comprising a helical resistor, granular magnesium oxid around and about the resistor, a tubular metal jacket surrounding the insulation and contracted crosswise to compress and com act the insulation, and terminals to the resistor and rigidly fastened to the jacket and closing the ends thereof.

11. An electric heater complete in itself, comprising an elongated tubular metal jacket, a winding resistor arranged therein, insulation compacted within the jacket and around and about the resistor, a terminal fastened to the jacket, and a connector having greater conductivity than theresistor and connecting the resistor and the terminal.

12. An electric heater complete in itself, comprising a helical resistor, connectors provided at the ends of the resistor and having greater conductivity than the. resistor, insulation around and about the resistor, a tubular jacket surrounding the resistor, and terminals fastened to the jacket and attached to the connector.

13. An electric heater complete in itself comprisin a helical resistor, connectors provided at t e ends of the resistor and having greater conductivity than the resistor, insulation around and about the resistor, a jacket surrounding the insulation and contracted crosswise thereon to compress and compact'the same, and terminals fastened to the jacket and connected to the connectors.

14. An electric heater complete in itself,

comprising a helical resistor, connectors provided at the ends of the resistor and aving greater conductivity than the resistor, insulation around and about the resistor, ajacket surrounding the insulation and contracted crosswise thereon to compress and compact the same, and terminals rigidly fastened to the jacket closing the ends thereof and having the connectors joined thereto.

15. An electric heater complete in itself comprising an elongated ductile tubular jacket, a helical resistor arranged within the jacket, granular insulation compacted withm the jacket and compressed upon the resistor to hold it and its convolutions in lace and to insulate the same, the jacket Being contracted crosswise to compact the insulation and compress it upon the resistor, and insulated terminals rigidl fastened to the jacket, one at each end t ereof, and having the resistor connected thereto.

16. A bendable electric heater complete in itself and havin in combination an elongated ductile tu ular metal jacket, terminals rigidly fastened to the jacket, one at each end thereof and insulated therefrom, a ductile helical resistor arranged within the jacket and connected to the terminals, and granular insulation compacted within the acket and compressed upon, around and about the resistor by crosswise contraction of the jacket.

17. An electric heater comprising an elongated ductile tubular metal jacket, a ductile helical resistor, arranged therein, insulation compacted within the jacket and compressed upon, around and about the resistor y crosswise contraction of the jacket to hold it in place and insulate it from the jacket and its convolutions from each other.

18. An electric heater comprising'an elonated ductile tubular metal jacket, a ductile elical resistor arranged therein, insulation compacted within the jacket and compressed upon the resistor to insulate it from the jacket and its convolutions from each other and hold it in lace, and terminals ri idly fastened to said from. v

19. An electric heater comprising a winding resistor, insulation compressed upon said resistor, and an elongated tubular jacket surrounding said insulation and con traoted crosswise to compact said insulation and compress it upon said resistor.

20. An electric heater comprising a helical resistor, insulation compressed upon said resistor, and an elongated ductile tubular jacket surrounding said insulation and contracted crosswise to compact said insulation and compress it upon said resistor.

21. An electric heater complete in itself comprising a helical resistor, insulation compressed upon said resistor, an elongated tujacket and insulated t eresulation within the jacket tion compacted within the jacket and compressed upon, around and about the resistor by crosswise contraction of the jacket.

23. The process of making an electric heater which comprises placing a winding resistor within a tubular metal jacket, fillin the space around and about the resistor an between the same and the acket with insulation, and contracting the jacket crosswise to compact the insulation and compress it upon the resistor, so that the resistor and its convolutions are firml held in place and the resistor insulated rom the jacket and its convolutions from each other.

24. The process of making an electric heater which comprises placing a helical resistor within and in spaced relation to a tubular metal jacket, compacting insulation between the resistor and the jacket, and contracting the jacket crosswise to compact the insulation further and compress it upon, around and about the resistor, so that the resistor and its convolutions are firmly held in place and the resistor insulated from the jacket and its convolutions from each other.

25. The process of making an electric heater which comprises assembling a helical resistor within and in spaced relation to a tubular meta-l jacket with granular in-. sulation therebetween, and contracting the jacket crosswise to compress and hold the in- 26. A process of making an electric heater characterized by positioning a helical resistor within a tubular jacket, inserting insulation within the jacket and packing it around and about the resistor, and contract ing the jacket crosswise to compact further the insulation and compress it upon the resistor,.so that the resistor and its convolutions are firmly held in place and the resistor insulated from the jacket and its convolut-ions from each other.

27. A process of making an electric heater characterized by positioning a helical resistor within a tubular jacket, inserting inand packing it around and about the resistor, and swaging the jacket to contract it crosswise and thus acket and its convolutions from each other. I i

and contracting the jacket crosswise to compact further the granular insulation and compress it upon the resistor, so that the resistor and its convolutions are firmly held in place and the resistor insulated from the jacket and its convolutions from each other.

characterized by positioning a helical re- S lStOI within a tubular jacket, inserting granular insulation within the jacket and 10 packing it around and about the resistor,

In witness whereof, I have hereunto subscribed my name.

l l l EDWIN N. LIGHTFOOT.

DISCLAIMER.

1,359,400. Edwin N. Lighffoof, New York, N. Y. ELECTRIC HEATER. Patent dated November 10. 1920. Disclaimer filed April 25, 1922, by the assignee, The Cutler-Hammer Mfg. Co.

Enters its disclaimer- To so much of claims 17. 19, and 20 of said patent, and each of them, as may corer an electric heater which is not bendable and not of such length or elongation that the resistor cannot be accurately and effectively centered or spaced with respect to the tubular metal jacket by tension imposed upon the resistor;

Thereby limit ng said claims 17, 19, and 20 of said patent, and each of them, to an electric heater which is bendable and of such length or elongation that the resistor must be centered or spaced mechanically and progressively in advance of and as the filling with the insulation proceeds and independently of the tension imposed on the resistor. j

Your petitioner further enters its disclaimer to so much of claims 23, 24, 25, 26, 27, and 28 of said patent, and each of them, as ma cover a process in which the resistor is not placed, assembled or positioned within the tubular metal jacket by positively and mechanically centering or spacing the resistor continuously and progressively in advance of and as the filling with insulation proceeds;

Thereby limiting said claims 23, 24. 25, 26, 27, and 28, and each of them, to a process of making an electric heater in which the resistor is placed, assembled or positioned within the tubular metal jacket by positively and mechanically centering or spacing the resistor continuously and progressively in advance of and as the filling with insulation proceeds.

[Oficia-Z Gazette May .9, JQZQJDI S'QLAI M E R.

1,359,400.-Ed/win N. Lightfoot, New York, N. Y. Euwrmo Huron. Patent dated November 16, 1920. Disclaimer filed October 18, 1923, by the assignee,

Tlw UutZer-Hammer Mfg. Co.

Hereby enters its disclaimer- To so much of claims 1, 2, 3, 4, 5, 15, 16, 18, 21 and 22 of said patent, and each of them, as may cover an electric heater in which the terminal or terminals are not tubular and do not have a portion extending into the end or ends of the tubular metal jacket;

Thereby limiting said claims 1, 2, 3, 4, 5, 15, 16, 18, 21 and 22 of said patent, and each of them, to an electric heater in WhlCh the terminal or terminal are. tubular and have a portion extending into the end or ends of'the tubular metal 'acket- To so much of claims 6, 7 and 8, of said patent, and each of them, as may cover an electric heater in which the terminals are not tubular and do not have a portion extending into the ends of the tubular metal jacket and are not secured thereto by the swaging of the jacket;

Thereby limiting said claims 6, 7 and 8 of said patent, and each of them, to an electric heater in which the terminals are tubular and have a portion extending into the ends of the tubular metal acket and are secured thereto by the swaging of the 'acket' lo so inuch of claims 9 and 10 of said patent. and each of them, as may cover an electric heater in which the terminals are not tubular and do not have a portion extending into the ends of the tubular metal jacketand are not secured thereto by the swaging of the jacket and to the resistor by the swaglng of the terminals;

Thereby limiting said claims 9 and 10 of said patent, and each of them, toan electric heater in which the terminals are tubular and have a portion extending into the ends of the tubularmetal jacket and are secured thereto by the swaging of the jacket and to the resistor by the swaging of the terminals.

[077501211 Gazette November 13, 1928.] 

